What are quantum computers and what role do they play in our future?

A quantum computer is a machine that is capable of exploiting the rules of quantum mechanics to provide solutions to extremely complex problems. We rely on quantum mechanics to explain the behaviour of very small particles and their interactions. Important applications of quantum mechanics include LEDs, microprocessors, medical and research imaging devices and electron microscopy.

Quantum computing development is gaining a lot of traction and scientists are achieving experimental results that, not long ago, we thought would be impossible. Researchers throughout the world are using a number of different approaches to tackle the remaining technological challenges to design and manufacture a general purpose quantum computing machine, known as the ‘gate-model’ quantum computer.

Where are we now?

At the Centre for Quantum Computation and Communication Technology, headquartered at the University of New South Wales and partner nodes at the University of Melbourne, Australian National University, University of Queensland, Griffith University, and University of Sydney in Australia, scientists have proven that a quantum version of computer code can be written and manipulated. This is done using a miniature version of a silicon-quantum computer manufactured in their laboratories.

D-Wave, a Canadian quantum computing company, has developed a quantum computer that aims to perform a specific type of quantum computing processing. This is referred to as a ‘quantum annealer’.

Traditional computers vs Quantum computers

The development of quantum computers is often linked to the fact that we are seeing limitations in the growth of the processing capabilities of modern computers. It is thought that quantum computers will somehow come to the rescue by providing greater processing powers. This is only partially true.

In reality, conventional computers and quantum computers operate based on two different paradigms, and it is likely that they will be used complementary. Conventional computers, which have now reached extreme processing powers, can be programmed to solve a broad range of computing problems.

Quantum computers on the other hand are inherently suitable to solve specific types of problems much faster than conventional computers. Such problems include:

  1. Machine learning related problems, such as face recognition and credit card fraud detection.
  2. Large integer factorization. This is one the bases for modern day cryptography.
  3. The simulation of quantum many-body systems, such as the positions and motions of planets, stars and other astronomical bodies.
  4. Optimisation problems that a traditional computer wouldn’t be able to solve within a reasonable amount of time. The travelling salesman problem is a good example. This involves calculating the most time efficient route from list of travel points.  

The main difference is that, despite the dramatic increase in processing speed, conventional computers still operate as mostly sequential machines that handle ‘binary digits’, or bits. A bit is either zero or one. The basic unit of information and building block of a quantum computer is a ‘quantum bit’, or qubit.

A qubit can be in a superposition of zero and one at the same time. In other words, a qubit can be zero, one, or any blend of zero and one together. This is very difficult for our ‘non-quantum’ brains to visualise, however, we can link it back to the famous Schrodinger’s cat that, as long as it was in the box, was dead and alive at the same time.

Storage environment very important

The superposition state of quantum bits in a quantum computer is extremely delicate and can be compromised very easily. For this reason a quantum computing chip must be hosted in a very unique environment, shielded from any radiation and kept at an extremely low temperature. Therefore, it is unlikely that we will see quantum computers sitting on our office desks. However, quantum computers hosted in dedicated locations may be used remotely using a traditional computer as an interface.

What does the future look like?

The implications of unlocking the computing power of quantum computers will be astounding. Quantum computers will be game changers in the finance, medical and cybersecurity industries. However, it is likely that to realise the full potential of this dream-machine, we will need to get our hands on one first.